@misc{cryptoeprint:2009:041,
author = {Yevgeniy Dodis and Salil Vadhan and Daniel Wichs},
title = {Proofs of Retrievability via Hardness Amplification},
howpublished = {Cryptology ePrint Archive, Report 2009/041},
year = {2009},
note = {\url{http://eprint.iacr.org/}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.